New Message: membership

A new message was posted:
Address: http://frontier.userland.com/discuss/msgReader$14359
By: Michelle (tanmich at student.vuw.ac.nz)
Hi,
Having difficulty finding my way round Manila Site.
Would you be able to tell how to change my settings so that:
When one wants to become a member of my site, they'd require authorisation from me before becoming a member.
So non-members may only view my homepage. Whereas, members that have been authorised (by me) to join, can view stories, and contribute to the discussions.
I do not want people to able to be a member simply by completing the "Join Now" form. i.e, I want to control who becomes a member.
How do I go about doing this?
This is a Manila site... http://manila.userland.com/.